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Andrew Reid

New information regarding H.265 on the Panasonic GH5

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58 minutes ago, Márcio Kabke Pinheiro said:

Newbie question: the image quality in 400 Mbit ALL-I will be better than 150Mbit IPB? Or is just to make editing more fluid?

(I was starting to evaluating ALL-I vs IPB in my E-M5 II, but I've returned it to Olympus for a refund - long story).

Well remember with the GH3, the ALL-I mode didn't quite have a high enough bitrate to maintain quality per-frame, for all those individual frames, so IPB looked a bit better.

Now 400Mbit/s is another story, it should be better than 150Mbit IPB, in same way 500Mbit MJPEG on the 1D C looks better - not a huge difference but there will be one. Big files sizes though!

Motion cadence should be the main thing that benefits in terms of image quality with ALL-I. But IPB is perfectly good at giving you individual frames with little compression, even at 150Mbit - and it's a nice big step up from 100Mbit on the GH4.

52 minutes ago, Jonathan Warner said:

So is that 400mbps ALL-I H264 for 4k 50/60p, or for 4k 25/30p?  

Because I think the 1DXii is 800mbps for 4K 50/60p and 500mbps for 4K 25/30p.  Please correct me if I'm wrong.

400Mbit ALL-I on the GH5 will be 4K 48p 10bit 4:2:2 and 30/24p.

4K 60p remains capped at 8bit 4:2:0 / 150Mbit IPB. As it is IPB, 150Mbit is reasonably enough.

C1zswoUXcAAiNFc.jpg-large.jpeg

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You are the first one I've seen reporting 4k 10bit at 48p. I can't really make sense of the chart, as it looks like 48p would be only 150 maps, but part of the summer 2017 firmware. Are you sure you're reading this chart correctly? Was it confirmed by Panasonic? Also, would it be selected in VF? 

DCI 4k 10bit at 48p would be massive.. Already decided to buy but didn't expect this!

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20 minutes ago, Stanley said:

24.00HZ, MOV/MP4,4096x2160,48P,400Mbps,422 10 Bit,All- Intra, Summer 2017.... Follow The Yellow grid.

Well spotted Simon.

I'm still hesitant. I'm reading 48p the same way as 50p and 59.94p is listed above it, with the chart indicating 150mbps. If you look at the top where you have 23.98 it's listing two bitrates. And then 3 bitrate options for all regular framerates. If 48p was possible in 400mbps wouldn't that be listed under 150mbps?

Let's see if Andrew can comment and clear it up if it's been confirmed from Panasonic

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I'm sorry, but I do not understand any of the reasoning behind why H265 is not used. I do not think it is correct that H265 cannot be used for intra. If H264 can be, so can H265.

And H265 is also supported in many editors now. H265 is also hardware decoded in all recent Intel chips; has been since at least the 6th generation (now in the 7th).

The inefficiency of H264 limits the quality of what we shoot if we want to stay with standard storage, like sd cards.

I think there is more to this than the faulty reasoning that was stated, and in any case it should not be applauded by video shooters.

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h265 - good for low bitrate. At hi bitrates ( for example - 4k 100mbps 24fps) it can`t hold noise as good as h.264.  Take nx1 and pixel pip at 200%... Details looks good, but the noise looks compressed...

400mbps 4k 60fps h264   video  can provide  lossless quality  with film-like noise

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21 minutes ago, tihon84 said:

h265 - good for low bitrate. At hi bitrates ( for example - 4k 100mbps 24fps) it can`t hold noise as good as h.264.  Take nx1 and pixel pip at 200%... Details looks good, but the noise looks compressed...

400mbps 4k 60fps h264   video  can provide  lossless quality  with film-like noise

At least that is an argument that makes sense. What does "compressed" noise look like?

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29 minutes ago, markr041 said:

At least that is an argument that makes sense. What does "compressed" noise look like?

Well, It looks like denoised noise. Skin becomes more plastic, but you still can see fine details. So 265 is only for stream video: really good looking in low bitrate. As you know h256 was made for delivery content to  mobile devices: small size, good IQ.

Check this image. Original footage from h265 cameras looks better, but blocking compression do something with overall details

 Sravnenie-h265.png 

Best example of hi bitrate h265fail - Look at the grain and man`s hand (yak)... In original resolution (this images was downscaled) the difference would be more obvious

compare-h264-h265-4.2_1.jpg

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From the info that Panasonic has in these charts, it looks like 48p will be just 150mbps 4:2:0 8bit IPB. 

1 hour ago, tihon84 said:

Best example of hi bitrate h265fail

H265 in the examples that you posted is 2% of the original H264 file size, and at these rates of course you are going to loose some detail compared to the original. The quality also depends on the implementation of each codec. 

The  BBC R&D video coding research team wrote a paper on this and concluded: 

"It can therefore be concluded that the HEVC standard is able to deliver the same subjective quality as AVC, while on average (and in the vast majority of typical sequences) requiring only half or even less than half of the bit rate used by AVC. This means that the initial objective of the HEVC development (substantial improvement in compression compared with the previous state of the art) has been successfully achieved."

Also, H265 can have an intra frame version the same way H264 has

From Wikipedia:

"The maximum bit rate of the profile is based on the combination of bit depth, chroma sampling, and the type of profile. For bit depth the maximum bit rate increases by 1.5× for 12-bit profiles and 2× for 16-bit profiles. For chroma sampling the maximum bit rate increases by 1.5× for 4:2:2 profiles and 2× for 4:4:4 profiles. For the Intra profiles the maximum bit rate increases by 2×"

And in the original H265 standards look for the "general_intra_constraint_flag". 

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So I should trust a site selling transcoder to h.265?
The thing is that larger blocks means less bandwidth per area, and that means less bandwidth for grain. I don't doubt H265 is great for clean material but the codec simply can't do magic. It can only take data from one area and prioritize it to another. And a good codec only hides what you can't see.in favor for what you can see.

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Since the AVC Ultra up to 30p is 400Mbps, it makes sense to be H.264.

As for 48p, it doesn't look like it's 10-bit 422, a H.264 400Mbps All-I codec wouldn't be enough for 48p, for AVC Ultra it would be around 640Mbps and even at a lower bitrate codec like Sony's XAVC-I, you would still need 480Mbps. Since there is no mention of 500-700Mbps All-I codec, I doubt that 48p will be All-I 10bit 422.

On the other hand Panasonic could very well provide a 200-240Mbps IPB 10-bit 422 codec for 4K60p if they wanted.

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